This invention relates to packaging materials, and more particularly to a packaging box, especially for products of the tobacco industry. This invention also relates to a blank for producing such a packaging box, of the type having a plurality of surface portions joined to one another by folding ribs, where the surface portions are intended subsequently to form faces or tongues of the package. The blank is formed in one piece. This invention further relates to a method of erecting such a blank.
The packaging industry has developed a great number of blanks intended, after folding and erection, to form the packaging of specific products, such as products of the tobacco industry, and in particular cigarettes. In this connection, a distinction is made between two kinds of cigarette packaging--viz., the so-called "soft pack," composed of one or more thin packaging sheets wrapped around a bundle of cigarettes, and the "box," produced from a thin cardboard blank and possessing a certain rigidity. It is to the latter type of packaging that the present invention relates. Cigarette packaging of this kind generally includes a box portion in which the cigarettes are contained and a lid portion hinged to the box portion. As a rule, the cigarettes are first wrapped in a composite sheet comprising an aluminized layer, then inserted in the box, which, after the lid is closed, is subsequently covered with a thin protective sheet of polypropylene or cellophane in order to keep the pack substantially hermetically sealed during storage.
Such packs, and blanks for forming them, are well known and are described, for example, in French Patent No. 1,207,982. The way in which the closure tongue of the pack shown in that patent is made leads to several drawbacks at the time of its manufacture and use. First of all, the pack includes a semicircular tongue 27, the making of which necessitates complicated tooling. After a closure tongue 8 is folded back inside the pack, and semicircular tongue 27 is glued no one or the other of the portions 34 or 36, two slits remain on the top edge of the face 3, at the ends of semicircular tongue 27, which prevents the finished pack from being sealed without an additional wrapper. Hence the pack must be supplemented by an additional sheet which covers the pack and is sealed in order that the pack of cigarettes may be moisture-proof during storage. This is important so that the tobacco will not dry out or lose its aroma and so that no foreign odors can penetrate into the pack. This additional wrapping requires several supplementary operations during preparation of the pack and furthermore generates added trash to be disposed of. Moreover, the fact that closure tongue 8 is disposed within the pack is a drawback insofar as it may easily be damaged when the pack is opened for the first time, when the pre-cut 21 is cut completely. Furthermore, since the closure tongue is inside the pack, it is inaccessible for opening the pack. There is no means of easily grasping the lid portion to be opened.
Each of the boxes disclosed in U.S. Pat. No. 4,890,440 and British Patent No. 2 031 386 requires a blank made up of two separate parts which have to be assembled during manufacture, thus complicating this operation and increasing the cost of the finished packaging.
The package described in U.S. Pat. No. 3,048,324 comprises a portion 53 which can be torn away, thus allowing the cover to be opened. A drawback of this packaging, according to the two embodiments described, is that it is made up of two superposed layers, thus increasing the use of raw material an its manufacture, hence the cost of the finished packaging. In Canadian Patent No. 670,668 and German (Fed. Rep.) Patent No. 22 07 449, the cover part is composed solely of a portion of the top surface of the packaging, which makes it difficult to reach the cigarettes in the pack.